[charentejohn]

Hope someone can help with this. My first post here having looked for an answer this forum seemed the best for solutions so here I am.

My strimmer died with rotted fuel pipes so I replaced them and the primer bulb, cleaned the carb and fuel tank and tried again. Couldn't get the fuel to come through so after much messing with the carb I bought a new one and have the same problem.

What happens is.....
Connect primer bulb to direct to supply and filter and pumps fuel perfectly, so I assue filter and primer are ok.
Connect in carb with primer bulb on the return side of the fuel system, inlet direct from fuel tank filter, and won't pump fuel. The bulb eventually ends up 'flat' and inflates again when pipe is disconnected.
I assume this means the fuel is not passing through the carb due to a blockage or closed valve ?

As the new carb is brand new I can only assume that it is not the problem, both old and new with the same problem is unlikely ?

If I connect the primer bulb to the inlet of the carb it pumps fuel but it just leaks fuel everywhere, just an experiment to see what happened.
So basically it will blow but not suck fuel through.

Any ideas appreciated as I can't think of anything else to try.

 

[30yearTech]

The inlet needle in your carburetor may be stuck on the new carburetor I have seen this before. If no fuel can be drawn through either carburetor then there is a restriction somewhere in the delivery, either in the fuel filter in the tank, a pinched line or in the carburetor. I am guessing you have an external primer as you did not post the brand and model of the trimmer.

 

[charentejohn]

Thanks for the info, I will check.
I was reluctant to dismantle a new carb but I can see how a needle could be stuck. These carbs are a world apart from what I am used to and so small that I can see that a small fault can cause a large problem.

I will do the check tomorrow and let you know what happens.

I like the comment of needing to know how it works to fix it. These are new to me and I am still trying to understand how they work. Previously I have scrapped fixable things like this but now think I should bite the bullet and figure out how to fix them.

The strimmer it is fitted to has no name on it (over 3 yrs old so I can't remember the name on the box) but is a good little unit. I only paid £100 new and the replacement carb cost £37 but as I like the strimmer I thought it best to fix it properly.
If I get it running I will repair the old carb for future use.

 

[dehrhardt]

If you go to the walbro web site, they have pretty good info about the operation of their carbs.